You can preview your render interactively via RenderMan's Image Tool or Render View.

More on rendering settings can be found in the ROP Node documentation

Using Image Tool

Set Display Device to "it" (the default)

Using Render View

Go to Render View.  Select your output, e.g. /out/ris1.  And press Render from inside the window.  

You may also render to disk/RIB